In various substrate processes of manufacturing a semiconductor, a liquid crystal display device, an optical disk, and the like, a temperature adjustment plate (a cold plate and the like) that controls a temperature of the substrate, or a shower plate that supplies a gas having a predetermined component to the substrate is used. These temperature adjustment plate and shower plate typically have a structure in which a passage that causes a heating medium and a gas to circulate therein is provided inside a metal plate made of aluminum, an aluminum alloy, and the like (for example, see Patent Literatures 1 to 3).
Such a plate with a passage is conventionally manufactured such that the passage is formed on a metal plate body by means of machining and the like, another plate that seals the passage (for example, a keep plate) is layered with a passage side of the metal plate body, and both plates are joined or adhered by means of a welding processing, brazing, or an adhesive.